Yeah, naaah, that's crap, Morgan.
He failed a gameday drug test for which the default penalty is four years.
He interfered with an anti-doping sample on two occasions for which the default penalty is four years. It's very hard not see two similar acts of cheating to be anything other than aggravating circumstances for which he could have gotten more than four years.
You, as usual, concentrate on the minutia and ignore the real issue. Even without your opinion that cannabis is not performance enhancing, and the anti-doping doctors do not agree with you, it is a clearly specified rule that failing a gameday drug test is a four year ban.
Plus, we do not know why he interfered on two occasions with the sample. Was he trying to hide something other than cannabis? Thats why, it is clearly stated that is the same as a failed test and guess what, four years. The Chinese drug cheat Sun got 8 years at CAS for doing it once, not twice.
As for the moaning about ending his career, well that was HIS choice. He knew the rules and decided to act in this manner KNOWING the consequences. If you don't want to ruin your career in professional sport, don't bloody cheat. There are no grounds for Rioli avoiding the known consequences for his actions.